In the manufacture of bedding and furniture, a mattress cover or other cushion is often fabricated from layers of different soft goods. Such mattress covers are typically made on wide-width multi-needle quilting machines and associated panel cutters such as those described in U.S. Pat. Nos. 5,154,130; 5,544,599; and, 6,237,517, all hereby expressly incorporated by reference herein.
For example, a mattress cover is often comprised of a stack of layers of different soft goods, which are often quilted together, that include a first, top layer of fabric ticking material, a second layer of a fiber material, a third layer of foam and a bottom layer of fabric backing material. Such a stack of compressible soft goods is about 2-6 inches thick and has a length and width corresponding to the size of the mattress cover being made. As part of the manufacturing process, it is necessary that the edges of the stack of soft goods be trimmed, so that the edges are straight and parallel. Known edge cutting machines have a motor-driven conveyor belt that transfers the stack of soft goods past a motor-driven compression roller and a pair of motor-driven cutting wheels. The compression roller compresses the stack of soft goods to a thickness of less than about three inches. A motor-driven cutting wheel is located on each side of the machine, and the cutting wheels must have a radius greater than the thickness of the compressed stack of soft goods, that is, at least about three inches.
While such a cutting operation is effective, it does have some disadvantages. First, the cutting wheel is relatively thin and has a tendency to bend or warp slightly from the cutting forces applied by the compressed stack of soft goods being moved past the cutting wheel by the conveyor. Thus, the cutting wheel has a tendency to drift or walk with respect to a desired straight cutting path, thereby producing a cut edge of the stack of soft goods that is rough and not straight over the length of the stack.
Second, the cutting wheel edge dulls with use and must be periodically sharpened. Therefore, a separate sharpening device is mounted adjacent the cutting wheel. In order to effect a sharpening cycle, the edge cutting operation is interrupted; and the sharpening device is manually or automatically moved into contact with the cutting wheel to execute a cutting wheel sharpening cycle. During the sharpening cycle, the cutting machine is out of production; and thus, the sharpening cycle reduces the efficiency of the machine operation and adds to the overall cost of the cutting operation.
In addition, the overall structure of the cutting machine is relatively complicated and costly. The cutting machine requires a motor-driven compression roller as well as a relatively wide motor-driven conveyor belt that provides a subjacent support for the stack of soft goods and moves it past the cutting wheel. A sharpener is also required, which has actuators that move the sharpener into contact with the cutting wheel; and often, a separate clamp is used. Such a system has different motors or actuators for powering the cutting wheel, the compression roller, the conveyor and for positioning the cutting wheel sharpener. Further, the operation of those actuators is often coordinated by a separate control. Such a complex cutting machine is expensive to build, operate and maintain; and that expense must be borne by the product, for example, the mattress cover, being trimmed on the cutting machine. This is particularly relevant to quilt manufacture.
U.S. Pat. No. 6,736,078, which is fully incorporated by reference herein, discloses an apparatus that included a variety of improvements to overcome these drawbacks. The patented apparatus includes a pair of powered conveyors, the upper conveyor including a system of links and springs within the upper conveyor. The upper conveyor functions to compress the soft goods and propel them through the machine. Each upper conveyor is tapered or sloped at its leading or upstream end. Consequently, the material or soft goods may roll back on itself as it is cut and propelled forward by the upper conveyors. Because of this issue, under some conditions, “dog earring” in the corners of the resultant cut panels may occur.
Therefore, there is a need for a cutting machine that reliably provides a clean and straight cut edge over the full length of the stack of soft goods, has a simpler and less costly structure, does not have material roll back and eliminates or reduces “dog earring” in the cut panel corners. This need especially exists in the manufacture of quilts such as quilted mattress covers, that are manufactured on a large-scale.